Vapor separating pump



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VAPOR SEPARATING PUMP Filed Feb. 25, 1949 2 Sheets-Sheet l i 1 HyL-l- May 8 19m M. L. EDWARDS VAPOR SEPARATING PUMP 2 Sheets-Sheet 2 Filed Feb. 25, 1949 ZesLowqZ/t Edwards Patented May 8, 1951 UNITED STATES PATENT OFFICE 3 Claims.

This. invention relates to a pump and motor assembly, particularly to a unitary booster pump and motor assembly for mounting within tanks as, for example, the fuel cell of an airplane.

The invention will hereinafter be specifically described as embodiedin an electric motor driven booster pump submerged within an aircraft fuel cell.

With the advent of high altitude performing aircraft, diiculties haveV arisen in supplying an ample feed of fuel from the vfuel cell or tank to the engine driven prunp during periods of high altitude flight. Many of .the diiliculties arise due to the volatile nature of the aircraft fuel. At high altitudes the fuel becomes more gaseous and the formation of gas or vapor bubbles is encoun# tered. Under such conditions, a normal feeding of fuel is not satisfactory because vapor locks` or air locks form in the fuel line to cause a rough running engine. Centrifugal pumps have been successfully employed to beat out these vapor bubbles at high altitudes and to pressure a constant supply of liquid fuel to the engine driven fuel pump.

However, since the' beaten-out bubbles tend to gather about the axial portion of the centrifugal pump in increasing volume during continued operation of the. booster pump, it is desirable to dissipate the bubbles Within the fuel cell away from the pump to increase the pump eiliciency.

Therefore, according to this invention, a centrifugal vapor separating pump assembly is equipped with a jet type pump or aspirator for removing the separated vapor bubbles from an annular vapor extraction chamber located above the pumping chamber. The jet pump receives a pressured stream of liquid from the discharge side of the vapor separating pump and produces an aspirator effect to draw the vapor from the extraction chamber and to discharge the vapor bubbles into the body of the fuel cell at a point spaced from the pump inlet and fuel pumping' chamber.

It is, then, an object of this invention to provide a bubble dissipator .for vapor separating pumps.

Another object of this invention is to provide an aircraft booster pump unit which effectively separates liquid and vapors and then propels the vapors away from the pump.

Another object of this invention is to provide a vapor separating and bubble dissipating pump which does not require more than one prime mover. A A specific object of this invention is to. provide type booster a unitary motor, vapor separating pump and bubble ejecting jet pump assembly of simplified construction.

Other andv further objects of the invention will be apparent to those skilled in the artfrom the following detailed description of the annexed sheets of drawings which, by Way of preferred example only, illustrate one specific vem bodiment of the invention.

On the drawings: t

Figure 1 is an elevational view of the pump assembly showing the booster pump in vertical cross section and showing the location of the jet pump with respect to the motor and booster Dump? Figure 1A is an enlarged fragmentary crosssectional view showing how vapor is taken off of the impeller;

Figure 2 is atop plan view along the line II-II of Figure 1 and showing parts in horizontal cross section;

Figure 3 is a vertical cross-sectional view of the .iet or vapor extracting pump taken along the line III-III of Figure 2. 1

As shown on the drawings:

In Figure l, the reference numeral l0 desig-` nates generally an electric motor pump unit according to this invention. A base casting I2 proe: vides much of the casing for the unit and also serves as a support for the unit I9, its lower porition lZa being of disk-like conguration for securing as by bolts i4 to the bottom wall `I6 of' a fuel cell. The bolts I4 are threaded Vinto a mounting ring i3 placed on the inner side of the bottom wall I 6 of the fuel cell and a circular gasket 28 is provided to prevent leakage of fuel from the cell through the bottom wall aperture lea which is provided for insertion of the unit il? within the cell.

The casting l2 supports an electric motor as4` sembly by a plurality of circumferentially spaced leg `portions |2b. An upper portion I2C of casting l2 is the bottom wall of the motor casing A22 and is secured to casing 22 by a plurality of bolts 24 threaded into the circumferentially spaced lobes 22a on casing 2,2. The rotor of the motor M carries a downwardly depending shaft '26 which projects through a central aperture in ashaft hub portion 12d of casting l2. An open bottom well 26 in the hub portion |2d receives a seal ring 28 loosely embracing the snaft 26 andis flxedly held in the bottom of the well by' a threaded sleeve -30 which is threaded into the hub lfd and presses against a washer 32 acting on the seal ring 28." .A rotating seal ring 35-rides 'on the stationary ring 28 and is spring urged against the ring 26 by means of a coil spring 36 surrounding the shaft 26 and bottomed on a boss portion 38h of an impeller hub 38a threaded onto the lower extremity of the shaft 26. A rubber sleeve 40 is sealingly engaged on the shaft 26 by means of a locking wire 42 and has a diaphragm portion extending over the seal ring 34 and clamped around the periphery of the ring 34 by the cap 44. Leakage along the shaft 26 is thereby effectively Stopped by the diaphragm member 4G and by the riding contact of the seal ring 28 and 34.

As previously mentioned, the motor shaft 26 depends downwardly through the sealing assembly and the hub portion I2d to receive an impeller hub 38a in threaded relation. Impeller 38 has a-flat disk portion 38o radiating from hub 38a thereof, and a ring of pumping vanes 38d are provided on top of the disk portion 38e in spaced relation from the hub 38a. Fuel from within the fuel cell enters this cham-ber l through a throat ring portion i2f of the casting I2, the throat portion I2f being centrally located about the shaft 26 in the same plane as the disk portion I2a of the casting I2. Thus it is obvious that the chamber 46 is located below the bottom wall I6 of the fuel cell. A downwardly extending' cylindrical portion I 2g of the casting I2 provides a pump casing for that part of the assembly below the bottom wall I6. The bottom wall i6 is closed by a cap 48. The cap 48, when removed, will permit a complete draining of the pump assembly and fuel cell.

' A generally annular insert ring 56 is disposed within the cylindrical .portion IZg of the casting I2 and has a groove 50a which defines a volute chamber 52 with the inner surface of the cap 48. The insert ring 50 also has a radially inwardly directed portion h which cooperates With `the throat ring portion I2f of casting I2 to form the annular vapor extraction chamber 54'. A narrow gap circular opening- 56 Ibetween the throat ring I2, and the radial portion 56h opens to the impeller chamber 66. As `best shown in Figure 1A, this gap 56 is radially outward from the inner edge of the impeller blade 38d. Since forced'rotation of iiuid in the chamber 46 begins at the inner leading edges of the ring of blades 38d, pressure of the fluid increases as the iiuid passes outwardly. This fluid pressure increases due to centrifugal force as the diameter of the fluid chamber increases. Therefore, vapor will be under positive pressure at any annular area outwardly from the inner edges of the blades, and, since the annular gap 56 is appreciably outward'from these inner edges, the vapor will be most effectively ejected. The insert ring 50 is closed at its top by a sealing gasket 56 and at its bottom by a sealing gasket 66. The sealing gasket 58 prevents the fiow of fuel from about the insert ring 50 into the vapor extraction chamber 54, and the sealing gasket S0 prevents the loss of fuel from the cell by escape from the volute chamber 52 about the cap 48.

It should be noted that the inner edges of the ring of varies or blades 38d lie on a circle having the same diameter as the circular inlet provided by the throat ring I2f while the annular gap 56 includes a diameter which is substantially greater. The inner ends of the blades 38d also terminate immediately adjacent the inlet.

In view of the foregoing description, it is apparent that fuel within the cell enters the separating chamber 46 by way of the throat ring I2f from whence it is pumped by the ring of rotated lighter than the liquid, will not be centrifugally discharged into the volute with liquid, since the vanes are effective to release these lighter materials from the liquid to rise into the collecting chamber 54. The fuel freed from vapors and under booster pump pressure leaves the assembly outlet passage 62 and enters the fuel discharge line 64.

The casting I2 has a generally cylindrical upright portion I2h which cooperates with the fuel line 64 in providing an outlet passage and is capped by the member 66 which is secured in place by the bolt 68 which also serves to secure the fuel line 64 to the casting I2. The fuel within the fuel line 613 is under booster pump pressure which is of course greater than the pressure of the fuel within the fuel cell.

The cylindrical portion I2h of the casting I2 communicates with a horizontal cylindrical portion I2i, the portion |21' forming the barrel section of the jet pump. A nozzle 'ill is threaded within the jet barrel I2z' withv its widest diameter opening communicating directly with the interior of the upright portion I2z. of the casting I2. The lesser diameter end opening of the nozzle "i0 communicates with the interior of the barrel Zz'. Fuel under booster pressure within the fuel line will enter the nozzle 'I6 through the larger diameter opening IIla and pass through the nozzle it] through the smaller diameter opening l'llc. A pipe I2 is threaded into the barrel I2i with its open end communicating with the interior of the fuel cell. The bracket l27` on the casting I2 supports the pipe l2. The fuel under booster pressure passing from the larger to the smaller diameter portion in the nozzle 'i6 increases the velocity upon leaving the nozzle, creating aspirator pressure within the barrel I2z' of Athe jet pump.

A vapor inlet pipe i4 is integral to and communicates with the jet pump barrel I2i to passage vapor from the vapor retraction chamber 54 into the cavity within the barrel I2i. The aspirator effect is well known in the art of jet pumping, and in this instance the low pressure area within the barrel I2i formed by the flow of fuel through the nozzle causes a vacuum to be created within the vapor extraction chamber 5t. Vapor bubbles are withdrawn from the pumping chamber 46 through the annular narrow gap opening 56 into the extraction chamber 54. The bubbles are then drawn into the pump barrel I2i through the vapor inlet pipe 1li. The pipe 'M additionally serves as a base vfor an additional motor support leg i6. The vapor bubbles are passed through the pipe 'I2 and escape into the fuel cell at a point well above the pumping chamber and directed generally away from the motorpumpunit I0.

From the above descriptions, it will be understood that the invention provides an improved airplane fuel system comprising a motor-pump unit with a jet vapor separating pump adapted to be submerged in airplane fuel cells wherein the motor driven booster pump will operate to pressure fuel to the engine driven pump, and the fuel pressure actuated jet pump operates to withdraw the vapor bubbles from the fuel in the motor-pump unit. The jet pump in withdrawing the vapor bubbles from the fuel within the motorpump unit will also withdraw a certain amount of liquid fuel through the narrow gap opening 56, but due to the size of the gap will not withdraw liquid fuel in great volume.

It will also be understood that the units of this invention can be completely inoperative without stopping the iiow of fuel from the fuel cell to the fuel line, since fuel can flow through the casing and impeller of the idle pump. During operation of the aircraft at relatively lower altitudes the vacuum pressure of the engine driven fuel pump is sufiicient to steadily flow the fuel through the pump impeller into the fuel line.

It will be further understood that various details of construction may be varied through a wide range without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In an aircraft fuel system, fuel cell, a pump disposed in said cell and having its inlet adjacent the bottom of said cell, a motor disposed in said cell for driving said pump, means on said pump defining a vapor collection chamber, an aspirator chamber discharging into said cell at a point remote from said inlet, a jet pump having its inlet communicating with the outlet of said rst pump and its outlet discharging into said aspirator chamber, a nozzle disposed in said jet pump and communicating with said jet inlet, and a duct between said aspirator chamber and said vapor collection chamber whereby vapors in said collecting chamber are withdrawn due to pressures created by the passage of fuel under pressure from said irst pump through said jet nozzle.

2. A vapor separating pump comprising a pump housing having an impeller chamber, a vaporreceiving chamber, a pumping chamber surrounding said impeller chamber and in communication therewith around the periphery thereof and an inlet at one end of the impeller chamber, an impeller having a ring of blades in said irnpeller chamber defining pumping channels therebetween and arranged to receive iiuids from the inlet along their inner ends to impart rotation to the fluids and release vapors therefrom, said blades having outer end portions arranged for CFI discharging liquids into the pumping chamber, means deiining a gap connecting the impeller chamber with the Vapor-receiving chamber at a zone radially outward from the inner edges of the vanes and at the upper ends of the vanes, an outlet for said vapor chamber, and an aspirator actuated by fluid from the pumping chamber for inducing ow through the outlet of the vapor chamber.

3. A vapor separating pump comprising a pump casing having a circular inlet adapted to be positioned at the bottom of a fuel cell, an impeller chamber in said casing receiving iiuids from said inlet, a pumping chamber receiving uids from the impeller chamber and an annular vapor outlet receiving vapor-rich iiuids from the impeller chamber, an impeller rotatably mounted in the impeller chamber and having circumferentially spaced pumping vanes therein, said vanes having inner leading edges adjacent the inlet terminating in a circle having substantially the same diameter as the inlet, and said annular vapor outlet including a diameter greater than said circle an aspirator chamber supported on said casing having a discharge opening spaced from said inlet, a jet pump having an inlet communieating with said pumping chamber and an outlet discharging into said aspirator chamber, and a duct between said annular vapor outlet and a point in said aspirator chamber adjacent said jet outlet.

MILES LOWELL EDWARDS.

REFERENCES CITED y The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 790,702 Nash May 23, 1905 1,780,679 Jennings Nov. 4, 1930 2,124,681 Jauch et al. July 26, 1938 2,418,221 Curtis Apr. 1,1947 2,461,865 Dams Feb. 15, 1949 2,463,251 Curtis Mar. 1, 1949 FOREIGN PATENTS Number Country Date 332,465 Great Britain July 24, 1930 

